This invention relates to a stator of an alternating current generator.
FIG. 11 is a sectional view showing a conventional alternating current generator. In the drawing, numerals 1 and 2 are a front bracket and a rear bracket made of aluminum constituting a case of the generator, and numeral 3 is a shaft provided inside the case and one end of the shaft is fixed in a pulley 4, and numeral 5 is a rotor of lundel-type fixed in the shaft 3, and numeral 6 is fans fixed in both sides of the rotor 5, and numeral 8 is a stator fixed in an inner wall of the case, and numeral 9 is a slip ring fixed in the other end (the opposite side of the end in which the pulley 4 is fixed) of the shaft 3 and the slip ring supplies a current to the rotor 5, and numeral 10 is a pair of brushes for sliding on the slip ring 9, and numeral 11 is a brush holder for receiving the brushes 10, and numeral 12 is a commutator electrically connected to the stator 8 and the commutator commutates alternating current output generated in the stator 8 into direct current output, and numeral 13 is a heat sink fixed in the brush holder 11, and numeral 14 is a regulator bonded to the heat sink 13 and the regulator controls an alternating current output voltage from the stator 8.
The rotor 5 comprises a rotor coil 15 for generating a magnetic flux by the flow of a current and pole cores 16 which sandwich the rotor coil 15 and form magnetic poles by the magnetic flux, and the pole cores 16 comprise a pair of a first pole core body and a second pole core body with the bodies engaging alternately.
The stator 8 comprises a stator core 17 and a stator coil 18 in which a conductor is wound on the stator core 17 and an alternating current voltage is generated by a change in the magnetic flux from the rotor coil 15 with rotation of the rotor 5.
In the alternating current generator shown in FIG. 11, by supplying a current from a battery (not shown) to the rotor coil 15 through the brushes 10 and the slip ring 9, the magnetic flux is generated and the first pole core body is magnetized in a north pole and the second pole core body is magnetized in a south pole. On the other hand, the pulley 4 is driven by an engine (not shown) and the rotor 5 rotates with the shaft 3 and thereby, a rotating magnetic field generated in the pole cores 16 is given to the stator coil 18 and an alternating current voltage is generated in the stator coil 18 by electromagnetic induction. The alternating current output generated in the stator coil 18 is commutated into direct current by the commutator 12 and also is controlled by the regulator 14 and is charged to the battery.
FIG. 12 is an enlarged perspective view of the stator of the alternating current generator shown in FIG. 11, and FIG. 13 is a detail view showing a structure of a neutral connection portion of the stator of FIG. 12.
A conductor constituting the stator coil 18 of the stator 8 is formed of a round conductor and comprises a receiving portion 18a received inside slots formed in the stator core 17 and a coil end portion 18b protruding to both sides of the stator core 17. Also, when the stator coil 18 is connected in a star in order to configure a circuit of a three-phase alternating current generator, a neutral connection portion 20 is formed in order to couple three conductor ends to make a neutral point and further output lines for sending the alternating current output generated in the stator coil 18 to the commutator 12 are included. Also, in order to recover output from a neutral voltage generated in the neutral point, an output outgoing line may be together coupled to the neutral connection portion 20 and in this case, four conductor ends are connected at the neutral connection portion 20.
Tough pitch copper is used in a conductor of the stator coil 18 and conventionally, the neutral connection portion 20 is bonded by soldering. Also, the soldered neutral connection portion 20 is coated with an insulating tube 22 and is inclined to the side of the coil end portion 18b in order to improve resistance to vibration and is fixed by varnish through the insulating tube 22.
Also, as a method of neutral connection, a method for fixing conductor ends using a bundling member and contacting to couple a different type of metal with good conductivity to the conductor end surface is disclosed in the Unexamined Japanese Patent Application No. Hei 7-115743.
The neutral connection portion of the stator of the conventional alternating current generator is configured as described above, and when solder is used as a bonding member of the neutral connection portion 20, there was a problem that a bonded portion is opened due to heat deterioration. Also, when Pb-containing solder is used in order to improve heat resistance of the solder, there were an environmental problem and a problem of a decrease in workability associated with an increase in melting point of the bonding member. Further, since a solidification shape is not stable in the solder, there is a possibility that a problem occurs in insertion into the insulating tube 22. Furthermore, for bonding using the solder, connection resistance increases due to deterioration of the solder, so that there was a problem that an increase in temperature of the bonded portion is accelerated and deterioration of the bonded portion is promoted.
Moreover, since bond strength is low in the bonding using the solder, a large area of the solder bonded portion is required and also, for fastening to a coil end portion, an insulating tube is always necessary for insulation and there was a problem that fastening strength is low in the fastening through the insulating tube.
Also, as a method of neutral connection, methods such as fusing and swaging have been proposed, but there was a problem of increase in a part count since a "terminal" to be used as a connection medium is required in any case and further, there was a problem of increase in a part kind since a terminal for connection corresponding to a sectional area of a conductor is required in order to bundle several conductors. Further, when the terminal is connected as a medium, a size of outer diameter of a neutral connection portion includes a thickness of the terminal, so that the diameter of the neutral connection portion increases and accordingly a diameter of the insulating tube to be fitted for insulation of a connection portion also increases, with the result that there was a problem that the conductors in the vicinity of the connection portion inside the insulating tube are difficult to fix and hold.